This issue presents a set of five papers reporting research findings in the diverse field of structural engineering. Areas of research range from development of an attenuation relationship for the assessment of seismic risk using gene expression programming (GEP) to investigation of damage mechanisms in cementitious coatings – crucial for fire protection – on steel members in bending. Brief summaries of these five papers are presented in the following paragraphs.
In the first paper, Amiri et al. (2015) present a procedure to develop an attenuation relationship for the assessment of seismic risk in different seismic zones in Iran. Authors used a GEP algorithm instead of the conventional constant regression model to obtain the attenuation relationship for the inelastic spectra. It is noteworthy that GEP is the natural development of genetic algorithms and genetic programming. A total of 954 horizontal ground motions recorded in 490 earthquakes are used. These events had surface wave magnitudes ranging from 4·0 to 7·7 with hypo-central distances in the range of 10–200 km. Inelastic spectra for the natural period range of 0·05–4 s are developed corresponding to displacement ductility ranging from 2 to 8. It is shown that the proposed algorithm can develop the model precisely as a continuous function.
The second paper (Al-Rousan, 2015) presents a parametric study of the behaviour of reinforced concrete thin-walled structures subjected to lateral loading based on non-linear finite-element analysis. To validate the numerical model, results obtained from the numerical analysis were compared with experimental results obtained from testing 22 model specimens. Good agreement was observed between the experimental and numerical results. This study highlighted influence of the height-to-diameter ratio and the reinforcement ratio on ultimate moment and shear capacity as well as on ductility of thin-walled reinforced concrete structures. The formation and propagation of cracks for specimens with and without openings are also examined.
Generally, it is accepted that voided reinforced concrete floor slabs in building structures have a lower shear strength compared with solid slabs owing to the reduction in their cross-sectional area. The third paper (Chung et al., 2015) established that the void shape and material of the void-shaper also influence the shear strength of voided slabs. To verify these assumptions, one-way shear tests were conducted for four test specimens: the first was a conventional solid slab and the others were voided slabs. The voids are of toroidal or doughnut shapes as well as non-doughnut shapes. The void-shaper is made of polypropylene plastic and glass-fibre-reinforced plastic. The test results show that the shear strength of doughnut-type voided slabs is 73–78% of a solid slab and is superior to that of existing voided slabs. The shear crack angle is found to change with the void shape. A finite-element analysis is presented to evaluate the influence of these parameters on the shear behaviour of the doughnut-type voided slab.
When determining the actual level of passive fire protection in a building in the aftermath of high intensity loading, it is very important to understand the performance and damage mechanisms of cementitious coatings and to develop methodologies to determine the in situ condition of cementitious coatings under such loadings. The penultimate paper (Chen et al., 2015) investigates damage mechanisms in cementitious coatings on steel members in bending. A series of monotonically loaded beam tests were conducted to observe the occurrence of cracks and their propagation leading to final failure. The experiments were then simulated using a cohesive zone finite-element scheme, capable of modelling interfacial damage between the coating and steel substrate as well as internal coating damage. The results of the experimental and numerical studies clearly reveal the distinct damage mechanisms of cementitious coatings on both tension and compression sides of structural steel members subjected to bending. Findings from this study provide practical methods to determine the condition of cementitious coatings on steel structures after a short-duration extreme loading event (earthquake, blast, windstorms), where there is minimal external damage to the building fabric or long duration damage from moderate levels of repeated non-monotonic loading.
The final paper (Varela et al., 2015) presents a numerical study of a control system to attenuate vibrations in buildings induced by traffic. Three-dimensional finite-element method numerical models were built to estimate dynamic characteristics. The models were calibrated through correlation with the experimental data obtained from an uncontrolled structure. The responses of the models suggest an alternative solution of the installation of prestressed slender steel pipe columns with rubber pads at their tops in between the floor slabs of the building.
This issue also includes reviews of two important books. The first review is carried out by Rafeeqi on the second edition of Delatte's Concrete Pavement Design, Construction, and Performance while the second review is presented by Aristizabal-Ochoa on the first edition of Structural Engineering of Transmission Lines by Peter Catchpole and Buck Fife. Based on the reviews it would appear that both books would be worthy additions for universities and organizations/institutes interested in structural engineering.
I hope readers will find this issue both exciting and informative.
